1. Field of the Invention
The present invention relates to a burner apparatus and, more particularly, to a burner apparatus that can be used in direct fired nitrogen vaporizers.
2. Description of the Prior Art
Direct fired nitrogen vaporizers have been used, for example, to supply nitrogen for use in various oil and gas production operations. Such vaporizers commonly burn diesel or similar liquid fuels. In a typical direct fired nitrogen vaporizer, the hot combustion gas generated by burning the liquid fuel is used to heat and vaporize a high pressured liquid nitrogen stream.
A typical direct fired nitrogen vaporizer includes a burner barrel wherein the liquid fuel is combined with air and is burned, a plurality of burner assemblies positioned in an end wall of the burner barrel, a fan that supplies air to the burner barrel, and a nitrogen tube assembly, similar to a tube/bundle heat exchanger, through which a high pressure liquid nitrogen stream flows. The high pressure liquid nitrogen stream flowing through the tube assembly is heated and vaporized by the hot combustion gasses flowing from the burner barrel. Each of the burners used in the burner barrel typically includes at least one liquid spray nozzle that is operable for spraying the liquid fuel into the burner barrel and a plurality of air slots extending radially around the periphery of the spray nozzle. The air fan operates to blow through these air slots and into the burner barrel. The flow of air from the air fan also forces the combustion gases generated in the burner barrel out of the burner barrel and through the nitrogen tube assembly.
A typical problem of prior art burner apparatuses used in direct fired nitrogen vaporizers is that there is incomplete mixing of the hot exhaust gases and the so-called secondary air that allows hot and cold areas to form in the heat exchanger. Additionally, the prior art burner apparatuses have suffered from the problem that there is a long flame front that can impinge directly on the combustion chamber and tube bundle in the exchanger, thereby shortening the life of these components. Additionally, it is not infrequent that there is incomplete combustion because of the large volume of fuel that is being sprayed from such a small area, i.e., a burner nozzle, resulting in smoke, high emissions of CO, and unburned fuel.